315 or 325 tires on early a?

I've had M/T ET streets that are 28" 12.5 wide and 325/60/15 that are about 13" wide. Both of these tire sizes will rub without a sway bar even if you mini tub to the frame rails. I found this out after I put my car on the road for it's first summer. That following winter I installed a sway bar from competition Engineering. The Et's never rub but when using the 325/60/15 and have more than one person in the car you'll hear them hit a little. That sway bar will also help plant your tires at the track. Jayson